This invention relates to a noise control system for an automobile. More particularly, this invention relates to a noise control system requiring only limited input for generating a noise control signal to enhance sounds produced by an automobile.
Active noise control systems for automotive applications are known for reducing or enhancing noise generated by a vehicle engine. An occupant within a passenger compartment of an automobile often can hear engine noises propagated through an air intake manifold. Typical active noise control systems include a speaker for generating a noise canceling or enhancing signal to provide an overall desirable engine sound. The speaker produces a sound determined with respect to current operating conditions of the engine to cancel or enhance engine noise as desired.
Typical active noise control systems require several different inputs from the vehicle engine for determining the necessary speaker output. Such information is acquired in some circumstances from a vehicle controller or by sensing directly from analog signals from various transducers. Each source of information requires a separate physical connection along with the accompanying control system support required to gather and use the information.
Some of the vehicle parameters that may be required to be read or predicted accurately include engine crank position, rotational speed, throttle opening, temperature, etc. The phase of the induction sound is sensitive to such parameters. Conventional systems rely upon many sensors to obtain information utilized in determining and generating a cancellation or enhancement sound.
Disadvantageously, multiple inputs from analog sensors or devices to the active noise control system add cost and use of information from the vehicle controller increases complexity. Either option requires relatively significant interfacing with existing vehicle electronics. Further, the required multiple interfaces with existing vehicle electronics and vehicle controllers have made an after-market noise control impractical.
Accordingly, is it desirable to develop a robust, durable and efficient noise enhancement system that can enhance sound quality within a passenger compartment while being simple to install and practical for after-market installation.